Incident Overview
At 1250 Pacific daylight time on April 30, 2010, a Cessna 170A (registration N5765C) experienced a left main landing gear collapse while landing at Minden-Tahoe Airport in Minden, Nevada. The aircraft was registered to a private party and operated by the pilot under 14 CFR Part 91. The flight, which departed Carson, Nevada at 1130, was an instructional flight for a tailwheel endorsement. Visual meteorological conditions prevailed, and no flight plan was activated.
Circumstances of the Landing
The certificated flight instructor (CFI) reported that the purpose of the flight was to practice for a tailwheel endorsement, with the pilot receiving instruction performing three-point landings. The first landing was described as “firm” due to a higher-than-normal sink rate. Subsequent attempts involved low passes to practice airspeed control. On the next landing attempt, the airplane swerved left. The CFI took control and corrected toward the runway centerline. While correcting, he heard a loud snapping noise followed by a loud scraping noise, and the airplane made a sudden left turn. The aircraft slid and came to rest on the left edge of the runway.
Damage and Examination
Post-accident examination revealed substantial damage to the fuselage and left wing assembly. Examination of the left main landing gear by an airframe and powerplant mechanic showed that the gear had fractured at the inboard end. Photographs of the fracture surface were sent to the NTSB Materials Laboratory for further analysis.
An NTSB senior metallurgist reported that the inboard fracture face contained a dark, crescent-shaped fracture on the lower aft surface, consistent with fatigue cracking. The remaining fracture surface displayed a coarse grainy appearance, clear chevron markings, and a shear lip, indicative of an overstress fracture. Corrosion damage was present on the worn surfaces of the left landing gear leg.
Consequences
The aircraft sustained substantial damage. The CFI and the pilot receiving instruction were not injured.